Conventional toothbrushes comprise uniform tufts of bristles each having a first end which is held captive in and fixed to a brush head, and a second end which is free and which is used for brushing. The free ends of the various tufts present a surface envelope which is capable of slight deformation by the bristles bending when they come in contact with a surface to be brushed, but which is incapable of adequately matching a surface having a complex shape. Such a complex surface is present in the mouth, wherein the teeth generally lie in a "C" shaped curve within the upper and lower jaw, each row of teeth consequently having a convex outer curve and a concave inner curve.
In toothbrushing the desire of users to cause the bristles to conform to the teeth is expressed by the forceful application of the brush to adequately deform the bristles to the arcuate contours of the dentiture. Such forceful application of the brush against the teeth merely leads to excessive wear of the tooth surfaces and gums, without adequate conformation of the brush to the teeth to provide the desired cleaning.
Toothbrushes having a flexibly neck located between the brush head, containing the bristles, and the handle have been disclosed in the prior art to provide conformation of the brush to the contours of the dentiture. Examples of such flexibly neck toothbrushes include the toothbrushes disclosed in U.S. Pat. Nos. 759,490 and 4,520,526. U.S. Pat. No. 759,490 creates neck flexibility by interposing a flexibly resilient material between a rigid brush head and handle, which flexibly resilient material may be reinforced with a second such type of material. U.S. Pat. No. 4,520,526 creates neck flexibility by the alternatives of either removing part of the material from the top and bottom of the neck portion of the brush, or having an oval shaped hollow in the neck extending from one side to the other. Such flexibly resilient toothbrush necks permit the bristle head to yield relative to the handle when excessive force is applied by the user, whereby the danger of injury to the teeth and gums is reduced. However, such flexure means do not allow the user the ability to control the contour of the brush head to the particular arch of the oral surface being brushed, to avoid the need to apply excessive force in the first instance.
U.S. Pat. No. 4,333,199 discloses a toothbrush whose head is pivotally mounted on a coiled spring above a recessed handle, such that the head is adapted to rotate and tilt as it is applied to the teeth. While such flexing action will allow the brush head to generally follow the arch of the oral surface being brushed, it provides no direct control by the user of the moving, tilting, rotating action of the toothbrush head.
PCT International Application WO 89/10076, discloses a toothbrush having the capability of varying the angle between the brush head and the handle in order to position the brush head in parallel with a arcuate section of the dentiture. WO 89/10076 discloses a toothbrush having a handle pivotally connected to the head, wherein the handle is formed of a pair of spaced apart, rigid, upper and lower sides, which sides are pivotally linked together to be movable lengthwise relative to each other. Alternatively, the spaced apart, rigid, upper and lower sides may be connected by means of an elastic spacer layer, which will also allow them to be movable lengthwise relative to each other. Use of a such a pivotally connected handle and head, controlled by the lengthwise movement of the rigid sides of the toothbrush, to accurately control the position of the toothbrush head is difficult at best. Such lack of precise control is due to the fact that pivoting linkages, which lack rigidity or resistance will tend to move the head excessively; while, the alternative use of an elastic layer will limit the movement of the head proportional to the degree of elasticity therein.
There is a need in the art for a toothbrush, wherein the position of the toothbrush head can be more precisely controlled by the user, to position the head in conformity with the arcuate configuration of the dentiture.